Apparatus and method for ensuring concentric weld deposition of material on a pipe interior

ABSTRACT

A welding jig for ensuring concentricity of an interior surface of a pipe with a circular outer periphery of a bolting flange thereon, comprising (i) a frame member; (ii) two spaced-apart rollers positioned at one end of said frame member, each adapted to remain in contacting engagement during welding with said circular outer periphery of said bolting flange; and (iii) a chill block, having a convexly-curved outer surface of a curvature corresponding to a desired inner diameter of said pipe, adapted to be positioned proximate said interior surface of said pipe. The rollers permit translational movement of the chill block about a center point of said pipe flange when the welding jig is placed on the pipe flange, to permit uniform diametrical deposition of weld material on said inner diameter of said pipe flange. A method of making a pipe is further disclosed and claimed.

CROSS REFERENCE

This application is a divisional application of U.S. application Ser.No. 12/881,877 filed Sep. 14, 2010.

FIELD OF THE INVENTION

The invention relates to a welding jig apparatus for ensuring uniformconcentric deposition of material to the interior of a pipe, and amethod for ensuring concentric deposition of material on the pipe'sinterior.

BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART

Hydropumping of hydrocarbon slurries over large distances is oftencarried out by pumping such slurries through large diameter (often 36inch/0.3 m or greater) pipe segments which make up an “oil” pipeline.

Due to the highly-abrasive nature of some of the slurries (such asbitumen when recovered from a tar sands recovery facility and whichtypically contains a substantial amount of abrasive sand), frequentlyelongate narrow-diameter (ie 0.25 in/0.63 cm) abrasion-resistantchromium carbide rods (alternatively called “wires”) are welded to theinterior of each pipe segment making up a pipeline, with a multitude ofsuch carbide rods extending longitudinally the length of the pipe andradially juxtaposed about the entire circumference of the interior ofeach pipe segment to thereby cover the entirety of the inner peripheryof each pipe segment and thereby increase the wear resistance of theinterior of each mild-steel pipe segment to abrasion. Alternatively,such wires may be circumferentially wound around the inner periphery ofthe pipe.

Pipes having the above chromium-carbide rods have been found to haveincreased abrasion resistance between 4 to 14 times as compared to thelifespan of ordinary mild steel pipe which lack chromium carbide rodoverlays.

The applicant Indutech Canada Ltd., using various specially-adaptedequipment and techniques, has for many years manufactured and suppliedabrasive-resistant piping having such chromium carbide rod overlayswelded to the interior of pipe segments, where such pipe segments are tobe used in hydropumping of slurries of crude oil and bitumen and wheresuch slurries are abrasive in nature.

Problematically, however, chromium carbide rods typically have asubstantially different co-efficient of thermal expansion than the outersteel pipe. Accordingly, during welding of the inner chromium carbiderods to the interior of the steel pipe and also when a mating flange iswelded to the pipe, the pipe inner diameter becomes non-concentric anddistorted (out of round). Moreover, due to the rod-like nature of therods when welded to the interior of the pipe, discontinues due to thenon-uniform nature of the rods exists,

This distortion and discontinuities between pipe segments is extremelyundesirable, since when bolting a pipe-flange assembly of one pipesegment to another similar pipe flange assembly of another pipe segmentin order to form a continuous pipeline, any distortion in the circularcontour of the inner pipe diameter at its mating edge with anotherflange assembly results in discontinuities in the interior surface ofthe pipe. Such discontinuities undesirably cause turbulence in the flowof the slurry within the pipe. Accordingly, when abrasive slurries arepumped through the pipe, undesirable and increased wear on the interiorof the pipe occurs at the areas of non-concentricity. This results ingreatly increased friction and wear at the points of discontinuity.

In addition to the detrimental effect on pipe wear life due to increasedwear, discontinuities in the pipe connections undesirably causeturbulence, which reduces the extent to which there is laminar flow offluid in the pipeline. Laminar flow in the pipeline (as opposed toturbulent flow) is greatly desired, as laminar flow results not only inless wear within the pipeline, but decreases the pumping pressurenecessary to pump a hydrocarbon slurry over a given distance.Accordingly, discontinuities in the interior pipe diameters at the pointof coupling of one pipe section to another results in higher pumppressures (and larger pumps) necessary than would otherwise be the caseif laminar flow was achieved to a greater degree in the pipeline.

In order to attempt to reduce the above problems, pipeline companieswhen purchasing abrasive-resistant piping frequently specify that theconcentricity and diameter of each mating flange be within certainstrict tolerances, in order to reduce or eliminate to the extentpossible the above undesirable conditions.

Accordingly, to meet the strict tolerances and concentricityrequirements of the pipe segment flanges and to thereby avoid theundesirable occurrence of discontinuities in the slurry flow from onepipe segment to another, skilled welders are required to “build up” theinner circular diameter of each pipe segment proximate each flangemember to a greater degree than necessary (ie with an excess carbiderods or weld material), and then grind down the “high” areas of the“overlay” to make the interior of the pipe flange of a fixed diameterand perfectly circular and concentric, so that when a similar flange isbolted to it there is a smooth transition at the point of abutment ofthe two pipe segments, and no turbulent flow is created.

Unfortunately, however, “building up” the inner area in such manner andthen grinding out the “high” spots to obtain a perfectly circular andconcentric inner pipe requires great skill, but even moreproblematically, is difficult to do and extremely time consuming andthus introduces considerable expense to the cost of manufacture of wearand abrasion-resistant pipe.

Accordingly, a real need exists in the art of manufacture ofabrasion-resistant pipe for an apparatus and method to more rapidly (andin a less labour-intensive and costly manner) produce abrasive-resistantpipe wherein the inner diameter (at least in the region of the matingflange) is concentric with and in a substantially uniform fixeddiametric relation with the circular outer periphery and/or bolt holepattern on the associated flange member, in order to reduce or eliminatediscontinuities in the interior of the resulting pipeline formed by thejoining of various abrasion-resistant pipe segments.

U.S. Pat. No. 4,850,524 entitled “VERTICAL STRIP CLAD WELDING METHOD ANDAPPARATUS” teaches a method and apparatus for welding vertical stripclad overlays into interiors of cylindrical vessels. Insofar as ispotentially relevant, such apparatus teaches, at col 3, lines 54-60, awelding shoe 70 which comprises a shoe mold 72 and a shoe insert 74. Theshould mold 72 is preferably of copper, and has cooling passage 75therein to permit cooling of the welding shoe. Notably, however, thepurpose of the device disclosed in U.S. Pat. No. 4,850,524 is to weldstrip cladding, and there is no disclosure nor provision on the weldapparatus to situate itself concentrically to a flange bolt pattern orcircular outer periphery of a flange for the purpose of ensuringconcentricity of the inner diameter of the cylinder with a bolt flangepattern.

US Publication 2008/0048010 entitled “CLADING COMPLEX PIPING GEOMETRY”teaches a mounting fixture for weld equipment used in weld overlyoperations on nozzles of a nuclear power generator pressurizer. Themounting fixture has a first ring which is adapted to be located aroundpressurizer pipe, having such mounting assemblies thereon for mountingto studs welded to a surface of the pressurizer, and a second regionspaced from the first ring, having a series of jacking assemblies whichcan be positioned against the pipe nozzle, and a series of support legs(item 46, FIGS. 3&4) connecting the first and second ring.

U.S. Pat. No. 6,953,142 entitled “METHOD AND APPARATUS FOR HOLDING AFLANGE” discloses an apparatus for locating and grasping a flange,having a number of clamp arms. Importantly, a number of pins are adaptedto move upwardly into flange holes within the flange for positioning theflange during the clamping action. Accordingly, the mounting fixture ofU.S. Pat. No. 6,953,142 is not for mounting on the interior of a flangedpipe to ensure uniform concentric deposition of weld material around theinterior of a pipe, and thus this patent likewise is only of backgroundinterest.

U.S. Pat. No. 4,496,097 entitled “AUTOMATIC BELLOWS WELDER AND METHODFOR USING SAME”, as shown in FIGS. 3 & 4 thereof and as described atcol. 3, lines 11-35, relates to a welding apparatus for welding twocircular plate members along a concentric annulus thereof to form a“convolution”. A pair of planar spaced-apart weld spools 22, and apressure roller 20 are provided, each arranged in a triangularconfiguration While the pressure roller 20 forces the diaphragms againstthe weld spools 22 and ultimately against each other to permit welding.While such is somewhat analogous to the present invention as set outbelow which uses a pair of rollers on the outside of the flange and thechill block as the effective pressure roller 20, notably, as expresslystated at col. 4, lines 35-40, such device “does not provide for chillit has been found that by this method of fixturing chill can beeliminated.” Moreover, such patent does not teach the spacing of anychill block a spaced distance to allow deposition of weld material, butmerely welds two flange type members together to form a bellows.

U.S. Pat. No. 5,942,289 entitled “HARDFACING A SURFACE UTILIZING AMETHOD AND APPARATUS HAVING A CHILL BLOCK”, as may perhaps be mostclearly seen from FIGS. 2 & 3 thereof, relates to a method and apparatusfor deposition of a hardfacing material 60 on a curved (see surface 42below) surface (see surface 42). A chill block 50 which has a radiusapproximately equal to (but greater) than the curved surface on theworkpiece upon which metal is to be deposited, is provided. Thedeposition head 48 and chill block 50 in a preferred embodiment aresupported together in fixed relation to each other and to the workpiece.The pipe 40 is rotated about its cylindrical axis, and molten materialis deposited on the exterior of the pipe 40. Notably, however, there isno triangular “fixation” of the chill block, on the interior of the pipeso as to maintain concentricity with an exterior flange, since theexterior of the pipe receives the deposition

Lastly, U.S. Pat. No. 6,711,804 entitled “MACHIING CENTER” teaches amachine center, having at least one work spidle unit which is mounted toorbit a central axis. The spindle can be positioned in a plurality ofpositions around the central axis, and may be moved in the radialdirection relative to the central axis. The purpose of the radialmobility of the work spindle unit is to permit location of tools alongvarious partial central path segments, for contact with the workpiece.Such patent does not teach an apparatus having exterior rollers (forpositioning on the exterior flange of a pipe), nor an interior chillblock which has a spring to bias it (against the interior of the pipeand thus concentrically within the pipe).

Accordingly, and despite the above prior art, a real need continues toexist in the art of manufacture of abrasion-resistant pipe for anapparatus and method to more rapidly (and in a less labour-intensive andcostly manner) produce abrasive-resistant pipe wherein the innerdiameter (at least in the region of the mating flange) is concentricwith and in a fixed uniform diametric relation with the circular outerperiphery and/or circular bolt hole pattern on the associated flangemember, in order to reduce or eliminate discontinuities in the interiorof the resulting pipeline formed by the joinder of variousabrasion-resistant pipe segments.

SUMMARY OF THE INVENTION

In order to overcome the problem of flanged pipes (and in particularabrasion resistant pipes having chromium carbide wear rods welded to theinterior of such pipes) having non-concentric interior diameters, and tomore quickly and economically produce pipe members having interiordiameters which are concentric with the circular outer periphery of thebolting flange and/or the circular bolt hole pattern therein, thepresent invention provides for a welding jig of a specific construction,and a method of manufacture of pipe members.

Broadly speaking, the invention comprises in one aspect a welding jig,which is adapted to overlie a planar face of a bolting flange on a pipe.The welding jig inter alia comprises (i) a frame member; (ii) twospaced-apart contact members positioned at one end of said frame member,each adapted to remain in contacting engagement during welding witheither said circular outer periphery of said bolting flange or twospaced-apart bolt holes in a circular bolt hole pattern in such flangemember; and (iii) a chill block.

The welding jig and associated chill block are adapted for use inwelding material over a portion of the inner peripheral surface of thepipe, making such portion substantially concentric and in a fixeddiametric relation to the bolt hole pattern and/or circular outerperiphery of the flange. A convexly-curved outer surface is provided onthe chill block, of a curvature corresponding to a desired innerdiameter of said pipe. Such outer surface on the chill block, and thechill block itself, are positioned (by the frame of the welding jig)proximate the interior surface of the pipe. After welded deposition ofmaterial over the incremental portion (inner surface) of thepipe/flange, rotational movement of the chill block and welding jigabout a center point of said pipe flange permit uniform diametricaldeposition of weld material on the entire inner diameter of the pipeflange.

Specifically, the welding jig is adapted to be incrementallyrepositioned to allow rendering another portion of the inner surfacesubstantially concentric with the bolt hole pattern or circular outerperiphery of the flange. The process is repeated until the entirety ofthe inner periphery of the pipe/flange is rendered concentric and in afixed uniform diametric relation to either the bolt hole pattern or thecircular outer periphery of the flange.

Accordingly, in a first broad embodiment, the invention comprises awelding jig apparatus for ensuring concentricity of an interior surfaceof a cylindrical pipe with either (i) a circular outer periphery of abolting flange, or (ii) a circular bolt hole pattern in said boltingflange; the welding jig comprising:

-   -   (a) a frame member, adapted to overlie a substantially planar        face of said bolting flange, in a position substantially        perpendicular to a longitudinal axis of said pipe, said frame        member comprising:        -   (i) at least two spaced-apart contact points, positioned at            one end of said frame member, each adapted to contact and            remain in contacting engagement during welding with said            circular outer periphery of said bolting flange or said bolt            hole pattern on said bolting flange;    -   (b) a chill block; situated substantially intermediate said        contact points but spaced therefrom, adapted to receive        therewithin a circulating fluid for the purpose of cooling said        block member, comprising:        -   (i) a convexly-curved outer surface, having a curvature            corresponding to a desired inner diameter of said pipe,            adapted to be positioned proximate said interior surface of            said pipe when said frame member overlies said bolting            flange;    -   wherein said frame member and said contact points thereon        maintain said curved outer surface of said chill block        concentric with said circular outer periphery of said bolting        flange and/or said bolt hole pattern during welding of material        on said inner surface of said pipe,

In another broad aspect of the present invention such inventioncomprises a welding jig for ensuring concentric weld deposition ofmaterial on an interior diameter of a pipe flange, comprising:

frame means, adapted to be positioned over a planar bolting face of saidpipe flange;

at least two spaced-apart contact points, positioned at one end of saidframe member, each adapted to contact and remain in contactingengagement during welding with said circular outer periphery of saidbolting flange on said pipe;

a chill block, mounted on said frame means a spaced distance from saidcontact points, having a convexly curved outer surface of a curvaturecorresponding to a curvature of an inner diameter of said pipe flange;

wherein said frame means and contact points means allow translationalmovement of said chill block about a center point of said pipe flange topermit uniform diametrical deposition of weld material on said innerdiameter of said pipe flange around an entire inner periphery of saidpipe flange.

In a preferred embodiment of the welding jig of the present invention,the contact points each respectively comprise roller means, and saidrollers means contact said circular outer periphery of said boltingflange and permit translational movement of said welding jig about saidcircular outer periphery of said bolting flange.

In yet a further preferred embodiment, the frame member of the weldingjig, at a distal end thereof opposite said contact points, possessesmeans to permit said distal end to overlie and be supported by saidbolting flange. Such means preferably comprise a pair of spaced-apartrollers, which further assist in the translational movement of thewelding jig about the circular periphery of the flange and about acenter of the pipe/flange.

In a further broad aspect of the present invention, such inventioncomprises a method for using a welding jig of the above design inmanufacturing pipe with an inner diameter concentric with either thecircular outer periphery of the bolting flange, or with a circular bolthole pattern on the bolting flange.

Accordingly, in another broad embodiment, the invention relates to amethod of manufacture of a pipe having a bolting flange at one endthereof, wherein an interior diameter of said pipe is formed so as to beconcentric with and in a fixed diametric relation to a circular outerdiameter of said bolting flange or a circular bolt hole pattern in saidbolting flange, comprising the steps of:

(A) placing a welding jig, having:

-   -   (a) a frame member, adapted to overlie a face of said bolting        flange, in a position substantially perpendicular to a        longitudinal axis of said pipe, said frame member comprising:        -   (i) at least two spaced-apart contact points, positioned at            one end of said frame member, each adapted to contact and            remain in contacting engagement during welding with said            circular outer periphery of said bolting flange or with a            corresponding number of bolt holes arranged on said bolting            flange;    -   (b) a chill block, situated substantially intermediate said        contact points but spaced therefrom, adapted to receive        therewithin a circulating fluid for the purpose of cooling said        block member during welding, comprising:        -   (i) a convexly-curved outer surface, having a curvature            corresponding to a desired inner diameter of said pipe,            adapted to be positioned proximate said interior surface of            said pipe when said frame member overlies said bolting            flange;    -   over said bolting flange so that said contact points engage        either (1) said circular outer periphery of said bolting flange;        or (2) a corresponding number of bolt holes in a circular bolt        hole pattern on said bolting flange, so as to maintain said        curved outer surface of said chill block concentric with said        circular outer periphery of said bolting flange or a bolt hole        pattern thereof and a fixed distance therefrom;        (B) welding a material, intermediate said chill block and said        inner surface, to said inner surface; and        (C) repositioning said chill block to a new position along said        interior surface of said pipe by moving said frame and contact        points an incremental distance along said outer periphery of        said bolting flange or along said bolt hole pattern on said        bolting flange; and        (D) repeating steps (B) and (C) until weld material has been        deposited along an entire inner peripheral length of said inner        surface.

In a refinement of the above method of the present invention, the twocontact points on the welding jig comprise a pair of rollers, adapted toengage and remain in contacting engagement with an outer circularperiphery of said bolting flange, and step (C) comprises the step ofrepositioning the chill block to a new position along said interiorsurface of said pipe by translational movement of said rollers, frame,and chill block about a center point of the pipe flange by rolling saidrollers about said circular outer periphery of said bolting flange to anew position.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and permutations and combinations of the inventionwill now appear from the above and from the following detaileddescription of the various particular embodiments of the invention takentogether with the accompanying drawings, each of which are intended tobe non-limiting, in which:

FIG. 1 is a perspective view of a first embodiment of the welding jig ofthe present invention, having a pair of rollers adapted fortranslational movement along the circular outer periphery of the boltingflange of a pipe, wherein the welding jig is positioned at a firstposition on the planar face of a pipe bolting flange, with the pipehaving longitudinally arranged chromium-carbide rods welded to theinterior of such pipe;

FIG. 2 is a similar (partial (perspective view of the first embodimentof the welding jig of the present invention shown in FIG. 1,repositioned on the planar face of a pipe bolting flange to a secondposition in order to show the manner of repositioning said welding jig,wherein the pipe in the drawing shown has a plurality ofcircumferentially-wound chromium-carbine rods;

FIG. 3. is a top view of the first embodiment of the welding jig of thepresent invention shown in FIG. 1;

FIG. 4 is a perspective side view of a further refinement of the firstembodiment of the welding jig shown in FIG. 1, having means to permitsaid distal end of the frame of the welding jig to overlie and besupported by said bolting flange, wherein such means comprises a pair ofspaced-apart rollers which assist in the translational movement of thewelding jig about the circular periphery of the flange;

FIG. 5 is a top view of a second embodiment of the welding jig of thepresent invention, shown overlying a bolting flange, wherein the twospaced-apart contact points, positioned at one end of said frame member,o contact and remain in contacting engagement during welding withcorrespondingly spaced apart bolt holes in a circular bolt hole patternon said bolting flange; and

FIG. 6 is a side perspective view of the second embodiment of thewelding jig of the present invention shown in FIG. 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference numerals in each of FIGS. 1-6 designate the identicalcomponents.

FIG. 1 shows a first embodiment of the welding jig 10 of the presentinvention, comprising a frame member 12 (which itself is substantiallyplanar and adapted to overlie a substantially planar face 14 of abolting flange 16 of a pipe 18). Welding jig 10, when used for thepurposes disclosed herein, is disposed on said bolting flange 16substantially perpendicular to a longitudinal axis 17 of pipe 18.

Pipe 18 typically is (although it need not necessarily be) anabrasion-resistant pipe, having a plurality of chromium-carbidewear-resistant rods 20 welded longitudinally along the interior surface22 of the pipe 18 as shown in FIGS. 1 & 3, or alternatively having aplurality of circumferentially wound chromium carbide wear-resistantrods 20 welded to the circumference of the interior surface 22 of pipe18, as shown in FIGS. 2 & 6.

Bolting flange 16 of pipe 18 typically possesses a planar surface 40,and has a circular outer periphery 26. A plurality of bolt holes 42 areprovided within a circular bolt hole pattern 44 on bolting flange 18,which are used for bolting two mating bolting flanges together to form acontinuous pipe. At least one or both of the circular outer periphery 26or the circular bolt hole pattern 44 are perfectly concentric aboutcenter point “C” of bolting flange 16 and pipe 18.

Two spaced-apart contact points 23 on welding jig. 10 in the form of twospaced-apart rollers 24 are provided at one end of frame member 12 inthe first embodiment of the welding jig 10 shown in FIGS. 1-4. Rollers24 in the embodiment shown in FIGS. 1-4 are each adapted to contact (andremain in contacting engagement during welding) with circular outerperiphery 26 of bolting flange 16. Circular outer periphery 26 in theembodiment shown in FIGS. 1-4 is perfectly concentric about center “C”of pipe 18.

Welding jig 10 further comprises a chill block 30, which as best shownin FIG. 3 is situated substantially intermediate said two contact pointsin the form of rollers 24 on welding jig 10. Chill block 30 is typicallycomprised of a highly thermally conductive metal, such as copper, and isadapted to be supplied via tubing 80 with cooling fluid. Specificallychill block 30 is adapted to allow cooling fluid to be provided to itfor the purpose of circulating within it to cool chill block 30 duringwelding, and provision is further made for connection to additionaltubing 81 to permit removal of such cooling fluid from chill block 30.For this purpose fluid inlet and outlet couplings, in the form ofstandard fluid coupling nipples 70, are provided on chill block 30, andare typically threadably inserted into chill block 30 to allow inlettubing 80 and outlet tubing 81 to be respectively connected thereto tosupply cooling fluid during welding.

Chill block 30 possesses a convexly-curved outer surface 34, having acurvature corresponding to a desired inner diameter (2× dimension ‘R’)of pipe 18 (see FIG. 3). Convexly-curved outer surface 34 is positionedby frame member 12 of welding jig 10 proximate the interior surface ofpipe 18, as shown in each of FIGS. 1-6.

Convexly-curved outer surface 34 of chill block 30 is held at a desireddiameter of the interior of pipe 18 by an elongate threaded member 36.Elongate threaded member 36 can be turned via turnbuckle 38 to adjustthe radial positioning of chill block 30 and curved outer surface 34thereon within the interior of bolting flange 16.

Because circular outer periphery 26 (in the embodiment shown in FIGS.1-4) is perfectly concentric about center “C” of bolting flange 16,curved outer surface 34 of chill block 30 can be maintained concentricwith center “C” by elongate members 50 of frame member 12 regardless ofthe radial position of the welding jig 10 on bolting flange 16. (eg. cfFIGS. 1 & 2). Specifically, chill block 30 is preferably centeredprecisely intermediate two contact points 23 (ie rollers 24) on circularouter periphery 26, and thus center of curvature of arcuate surface 34will precisely fall at center point “C” of pipe 18. This is because ofthe geometric principle that a line perpendicular to and which equallybisects a line connecting two points on the periphery of a circle neednecessarily pass through the center of the circle. Elongate threadedmember 36 preferably passes through center point “C”, as best shown inFIGS. 2 & 6, in order that arcuate surface 34 be concentric withcircular outer periphery 26.

Where circular bolt hole pattern 44 on bolting flange 16 is alsoconcentric about center point “C”, and where the outer periphery 26 ofbolting flange 16 may or may not be perfectly circular or not perfectlyconcentric about center point “C”, in such circumstances an alternativeembodiment and manner of operation of the welding jig 10 of the presentinvention is provided, as shown in FIGS. 5 & 6.

Specifically, in such embodiment where circular bolt hole pattern 44 onbolting flange 16 is concentric with center “C” of bolting flange 18,welding jig 10 as shown in FIGS. 5 & 6 is provided with a pair of spacedapart contact points at one end of jig 10 in the form of removable pinmembers 60, which may each be inserted in a corresponding pair of boltholes 42 within circular bolt pattern 44. As chill block 30 is centeredprecisely intermediate two contact points (ie removable pin members 60)on circular outer periphery 26 as shown in FIGS. 5 & 6), chill block 30and in particular convexly curved surface 34 thereof will be keptperfectly concentric about center “C” of bolting flange 18.

Removable pins 60 (which serve to position welding jig 10 on boltingflange 16 so that arcuate surface 34 is concentric with circular bolthole pattern 44) are of a diameter substantially corresponding to boltholes 42 within flange member 16, and may be provided with grippingmembers 61 which facilitate easy handling and prevent pins 60 fromslipping through bolt holes 42.

In a preferred embodiment of the welding jig 10 of the presentinvention, at a distal end 72 thereof opposite contact points 23possesses means to overlie and be supported by bolting flange 16. In apreferred embodiment such means comprises a pair of rollers 24 disposedon elongate arms 75, as most clearly shown in FIGS. 1,3, 4,5,& 6. In apreferred embodiment as shown in FIG. 4, adjustment means 76 such asshown in FIG. 4 may be provided on elongate arms 75 of frame 12 to allowrespective adjustment of the position of rollers 24 overlying boltingflange 16.

The manner of operation of the welding jig 10 in creating a pipe 18having a flange 16 wherein the interior surface 22 thereof is madeconcentric with the circular outer periphery 26 of the bolting flange 16and/or the circular bolt hole pattern 44 on bolting flange 16 will nowbe described in detail.

Welding jig 10 is placed over planar face 14 of flange 16, substantiallyperpendicular to longitudinal axis 17 of pipe 18.

In an instance where the circular outer periphery 26 of bolting flange16 is perfectly circular and concentric about center “C” of flange 16, awelding jig 10 as shown in FIGS. 1-4 is used, having a pair of spacedapart contact points 23 in the form of rollers 24, which are placed incontact with the circular outer periphery 26 of bolting flange 16.Arcuate curved surface 34 of chill block 30 is positioned via turnbuckle38 on elongate threaded member 36 against the inner surface 22 of pipe18, at a distance “R” corresponding to the desired uniform radius ofinner surface 22 of pipe 18.

Cooling fluid is provided via tubing 80 to chill block 30, and removedfrom chill block 30 via additional tubing 81. Weld material usingwelding gun (typically tungsten inert gas welding gun, but other formsof welding may be used as will occur to a person of skill in the art),to uniformly deposit material (typically wear resistant material) in theinterstitial distance between existing wear material on inner surface 22of pipe 18, and the arcuate curved surface 34 of chill block 30.

Upon solidification of such deposited material on the inner surface 22of pipe 18, welding jig 10, and in particular rollers 24 in contact withcircular periphery 26, is repositioned by sliding rollers 24 alongcircular periphery 26, thereby moving chill block 30 and curved surface34 thereof to a new position contacting inner surface 22 of pipe 18.Repositioining may be assisted by use of handle member 100 positionedintermediate rollers 24 proximate points of contact with circularperiphery 26.

To reposition such arcuate surface 34 and welding jig, it may benecessary to unscrew turnbuckle 38, reposition welding jig 10, andrescrew turnbuckle 38 to return arcuate surface 34 of chill block 30 tothe desired radial position “R”.

The above welding and repositioning steps are sequentially repeated asthe chill block 30 is incrementally repositioned around the innercircumference of pipe 18, until the entirety of inner surface 22 of pipe18 has had weld material uniformly deposited thereon, thereby producingan inner surface 22 of a diameter concentric with the outer periphery 26of bolting flange 16.

In an instance with regard to a bolting flange 16 on a pipe 18 has acircular bolt hole pattern 44 perfectly circular and concentric withincenter “C” of pipe 18, and particularly in a situation where outerperiphery 26 of bolting flange 16 is not perfectly circular and/or notconcentric with center “C” of pipe 18, a welding jig of slightlymodified configuration is used, namely of a configuration as shown inFIGS. 5 & 6.

Specifically, in such situation, welding jig 10 is provided with twocontact points in the form of insertable pins 60, apertures for suchpins 60 being provided a predetermined distance apart in frame 12corresponding to the shortest distance between a predetermined number ofbolt holes 42 on bolting flange 16. Jig 10 is placed over planar face 14of bolting flange 16, and pins 60 inserted within a pair of bolt holes42 within circular bolt hole pattern 44, to thereby stabilize andtemporarily secure jig 10 to bolting face 16 of pipe 18. Curved surface34 of chill block 30 is positioned at a desired radial distance “R” (thedesired uniform and concentric radius of pipe 18 which is desired to becreated) via turnbuckle 38 on elongate threaded member 36.

An identical procedure identical to the process described above inrespect of the alternative embodiment of the welding jig 10 is thencarried out, namely a cooling fluid is supplied to the chill block 30,and a weld material 85 is built up by weld deposition in theinterstitial area between the inner surface 22 of pipe 18 and thearcuate curved surface 34. Upon solidification of any weld material,pins 60 are then raised, and the welding jig repositioned by anincremental rotation about center point “C”, which repositioning may beassisted by use of handle member 100. Again, it may be necessary tounscrew turnbuckle 38, reposition welding jig 10, and rescrew turnbuckle38 to return arcuate surface 34 of chill block 30 to the desired radialposition “R”.

Many variations and modifications will now occur to those skilled in theart.

For a complete definition of the invention and its intended scope,reference is to be made to the summary of the invention and the appendeddams read together with and considered with the disclosure and drawingsherein.

1. A method of manufacture of a pipe having a bolting flange at one endthereof, wherein an interior diameter of said pipe is formed so as to beconcentric with and in a fixed diametric relation to a circular outerdiameter of said bolting flange or a circular bolt hole pattern in saidbolting flange, comprising the steps of: (A) placing a welding jig,having: (a) a frame member, adapted to overlie a face of said boltingflange, in a position substantially perpendicular to a longitudinal axisof said pipe, said frame member comprising: (i) at least twospaced-apart contact points, positioned at one end of said frame member,each adapted to contact and remain in contacting engagement duringwelding with said circular outer periphery of said bolting flange orwith a corresponding number of bolt holes arranged on said boltingflange; (b) a chill block, situated substantially intermediate saidcontact points but spaced therefrom, adapted to receive therewithin acirculating fluid for the purpose of cooling said block member duringwelding, comprising: (i) a convexly-curved outer surface, having acurvature corresponding to a desired inner diameter of said pipe,adapted to be positioned proximate said interior surface of said pipewhen said frame member overlies said bolting flange; over said boltingflange so that said contact points engage either (1) said circular outerperiphery of said bolting flange; or (2) a corresponding number of boltholes in a circular bolt hole pattern on said bolting flange, so as tomaintain said curved outer surface of said chill block concentric withsaid circular outer periphery of said bolting flange or a bolt holepattern thereof and a fixed distance therefrom; (B) welding a material,intermediate said chill block and said inner surface, to said innersurface; and (C) repositioning said chill block to a new position alongsaid interior surface of said pipe by moving said frame and contactpoints an incremental distance along said outer periphery of saidbolting flange or along said bolt hole pattern on said bolting flange;and (D) repeating steps (B) and (C) until weld material has beendeposited along an entire inner peripheral length of said inner surface.2. The method as claimed in claim 1, wherein said two contact points onsaid welding jig comprise a pair of rollers, adapted to engage andremain in contacting engagement with an outer circular periphery of saidbolting flange, and step (C) comprises the step of repositioning saidchill block to a new position along said interior surface of said pipeby translational movement of said rollers, frame, and chill block abouta center point of said pipe flange by rolling said rollers about saidcircular outer periphery of said bolting flange to a new position.